1. Field of the Invention
The present invention pertains to a gravel pack screen for fluid-producing wells which is modified to include a medium which will temporarily provide a barrier to fluid cross-flow in over- or under-balanced wells and similar situations.
2. Background Art
In the art of producing fluid from wells wherein gravel packing of the wellbore is required, or desirable, there are situations wherein the formation zone which is to be produced has a significant pressure gradient with respect to the distance along the wellbore. In such situations, a problem arises when attempting to install gravel pack screens of the auger type wherein wellbore fluids flow into the gravel pack screen at one location and, due to the pressure gradient along the gravel pack screen, tend to flow out of the screen at another location along the wellbore. This fluid cross-flow is undesirable and should be avoided at least during installation of gravel pack screens, such as of the auger type.
U.S. Pat. No. 5,063,920 to Cornette et al and assigned to the assignee of the present invention describes one improved gravel pack well completion having an auger-type gravel pack screen. U.S. Pat. No. 5,145,004, issued Sep. 8, 1992, and U.S. patent application Ser. No. 668,003, filed Mar. 12, 1991, both in the name of Holley M. Cornette and assigned to the assignee of the present invention describe certain other improvements in auger-type well gravel pack screens. These gravel pack screens as well as certain other types of gravel pack screens may be modified by the present invention to minimize the above-mentioned problem associated with auger-type well gravel packing completions.